An internal ballistic model of electromagnetic railgun based on PFN coupled with multi-physical field and experimental validation

To accelerate the practicality of electromagnetic railguns,it is necessary to use a combination of threedimensional numerical simulation and experiments to study the mechanism of bore damage.In this paper,a three-dimensional numerical model of the augmented railgun with four parallel unconventional rails is introduced to simulate the internal ballistic process and realize the multi-physics field coupling calculation of the rail gun,and a test experiment of a medium-caliber electromagnetic launcher powered by pulse formation network(PFN)is carried out.Various test methods such as spectrometer,fiber grating and high-speed camera are used to test several parameters such as muzzle initial velocity,transient magnetic field strength and stress-strain of rail.Combining the simulation results and experimental data,the damage condition of the contact surface is analyzed.

A SIMULATION STUDY OF DEPOSITION UNDER TWO TYPES OF IMPINGING TRAJECTORIES

A model coupling particle aggregation and randomwalk surface diffusion has been developed for 2D simulation of depositional growth, in which impinging particles follow either a straight-line trajectory of cosine distribution, representing typically sputter deposition, or a scattered trajectory, representing typically electrochemical deposition. Simulations of the growth under various impinging conditions and effective surface diffusivity have been carried out. Pattern and defect development in deposition on flat, trenched and ridged substrates have been investigated. We found that on flat and ridged substrates, both types of trajectories yield similar features, including formation of cone-like defects on surface ridges. While on trenched substrate, the straight-line impingement yielded more uniform step coverage than the scattered impingement.

Allowed Spatial Transitions and Cancellation of the Richard­son-Langmuir Ban

The ancient emission formulas of Langmuir and Richardson entered the calculations of subtle effects in semiconductor devices as basic ones.But,in the physics of semiconductor devices,these models have long played a purely decorative role,since they can describe in the most rough approximation only individual sections of the I-V characteristic.But it is precisely the fact that these formulas are basic when describing the barrier current-voltage characteristics(CVC)and prevented the consideration and use of thermoelectric effects in materials on a nano-scale.Thus,as these basic emission models actually imposed a ban on the MEASURABILITY of local thermoelectric effects,the existence of which has already been proven both phenomenologically and experimentally.The quantum transition technique is based on classical models.But it can also be used to correct these classic formulas.The calculation of the spatial transition of electrons over the potential barrier,taking into account the polarity of the kinetic energy,gives currents that are significantly higher than the currents of Langmuir and Richardson,including in the initial section of the I-V characteristic.Moreover,ballistic currents are concentrated at energy levels close to the threshold.This effect of condensation of electrons flowing down the barrier transforms the"anomalous"Seebeck coefficients into normal MEASURABLE Local Thermal EMF,including in p-n junctions.

Scaling relation of domain competition on(2+1)-dimensional ballistic deposition model with surface diffusion

During heteroepitaxial overlayer growth multiple crystal domains nucleated on a substrate surface compete with each other in such a manner that a domain covered by neighboring ones stops growing.The number density of active domains ρ decreases as the height h increases.A simple scaling argument leads to a scaling law of ρ~ h^（-γ） with a coarsening exponent γ=d/z,where d is the dimension of the substrate surface and z the dynamic exponent of a growth front.This scaling relation is confirmed by performing kinetic Monte Carlo simulations of the ballistic deposition model on a two-dimensional（d=2） surface,even when an isolated deposited particle diffuses on a crystal surface.

Hitting point tracking control of tank projectile based on Chebyshev exterior ballistic polynomial:an adaptive robust feedback approach

In this paper,the tracking control problem of the projectile hitting point of the moving tank is studied.First,a multi-body dy-namic model with stability systems is established.Second,the nonlinear coupling dynamic equation of turret-barrel pointing system is established.Third,the trajectory equation of exterior ballistic(EB)projectile in six degree-of-freedom is established,and the pointing problem was transformed into a problem of hitting point tracking through coordinate transformation.Forth,an adaptive robust feedback control method is proposed to make the predicted hitting point tracking the expected position accurately.Finally,Chebyshev surrogate model is used to replace the EB differential equation,which effectively reduces the time required by co-simulation.This paper combines the EB process with the tracking control problem,which effectively ensures the first-round chance of hit for the tank gun.